Gemstone Polishing Device and Method of Polishing

ABSTRACT

A method of polishing diamonds held by a tang ( 100 ) having a predefined axis ( 160 ) orthogonal to polishing surface ( 110 ). The axis ( 160 ) returns to its original spatial orientation with respect to the polishing surface ( 110 ) at the end of each facet of the diamond ( 122 ) polishing.

FIELD OF THE INVENTION

The present device relates to the field of gemstones polishing devices, and particularly to the devices for polishing diamonds.

BACKGROUND

Diamonds are polished on a rotating polishing wheel. For polishing, they are held with the help of a dop and a tang. Tang is an elongated device consisting of two main parts: the rear end or butt and the front part or clamp that extends forward from the butt. Usually two screws are inserted in the rear end of the tang. Rotation of the screws in the course of the leveling process changes the spatial position of the tang. The front end of the tang is usually an assembly of a number of parts such as dop and dop holder that allows for dop rotation or facet switching.

When polishing of the first facet is completed the tang with the dop holding the diamond are leveled in such a way that one of its axes becomes orthogonal to the polishing surface. The assembly of the dop and dop holder however, is not rigid enough and when the polisher switches from one facet to the next, or slides with the tang on the table around the polishing wheel, the assembly changes its spatial position. This spatial position change has a negative effect on the facet angle of the polished diamond.

It would be desirable to have a tang that when switched from one facet to the next, or sled on the table around the polishing wheel, it does not change and in particular the assembly its spatial position.

International Patent Application Publications Nos. WO 2004/035261 A1, WO 2004/035264 A1 and Israeli Patent Application Number 151195 to the same Assignee describe different tangs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the tang and the polishing wheel;

FIG. 2 is a schematic cross sectional cut of front part of the tang of FIG. 1, and

FIG. 3 is a schematic illustration of the tang leveling sequence with a level placed on a pedestal.

FIG. 4 is a schematic illustration of another embodiment of the tang;

DETAILED DESCRIPTION

FIG. 1 is a schematic illustration of a device for polishing diamonds. Device 100, which is a tang, includes an elongated body 102 having a rear part 104 and a front part 108. Rear part 104 houses two spaced apart screws 112 and 114. Rotation of screws 112 and 114 changes the spatial position of tang 100. Change of spatial position may be performed in both pitch 118 and roll 120 direction. Disposed in front part 108 are a removable linear level 124 and a conventional dop 128 for holding a gemstone or a diamond 122 in course of the polishing operation. Dop 128 supports rotation of gemstone 122 from one facet to another facet as well as gemstone polishing angle adjustment. Numeral 110 marks a polishing surface of a polishing wheel 116.

FIGS. 2 is cross sectional cut of front part 108 of tang 100. Front part 108 further includes a fixed insert (bushing) 130. Insert 130 is held in place by a fixing screw 134. Alternatively, insert 130 may be a tight fit insert pressed in front part 108 of tang 100. Insert 130 is substantially longer than the thickness t of front part 108 and it has its upper end face 138 and lower end face 136 machined. An assembly 142 that includes a mushroom form pedestal 140 and dop holder 144 is located in front end 108. Pedestal 140, or any other arrangement for holding level 124, has guiding means 146, which may be a protrusion or a recess or simply flat surface and a tubular cylindrical stem 148. Guiding means 146, which are shown as a protrusion, serve as an axis for level 124 rotation. The outer surface of stem 148 mechanically interfaces with the inner surface of insert 130 and actually resides within insert 130. The inner surface of stem 148 couples with dop holder 144. Holder 144 has a section 152 having external diameter larger that the external diameter of insert 130. Surface 156 of section 152 that is in contact with surface 136 of insert 130 is machined.

The length of stem 148 is divided into two sections. One of the sections 150 that extends from pedestal 140 has a diameter larger than the rest of stem 148. Section 150 ends by a steep edge leaning on machined end face 138 of insert 130. Screw 154 tensions and locks dop holder 144 with stem 148 and with insert 130. Screw 154 locks extension 148 to machined end face 136 of insert 130 against a spring 158. Dop holder 144 couples with stem 148 of pedestal 140 and subsequently with insert 130 along a common axis 160. Pin 164 associated with dop holder 144 engages a slot in stem 148 and prevents rotation of dop holder 144 relative to pedestal 140. Axis 160 defined by the assembly of pedestal 140 and dop holder 144 has a fixed spatial position with respect to elongated body 102 of tang 100.

Stem 148 further includes two O-rings 168 and 170. O-rings 168 and 170 are hermetically closing the mechanical interface between stem 148 and insert 130. O-rings 168 and 170 sit tight within insert 130, providing enough friction that prevents occasional rotation of assembly 142, of pedestal 140 and dop holder 144 relatively to elongated tang body 102 during the polishing. In addition, O-rings 168 and 170 prevent dirt and abrasive dust that may be present in the course of the gemstone or diamond polishing process from entering into the interface area.

For polishing a diamond tang 100 is leveled by screws 112 and 114 in such a way, that axis 160 becomes orthogonal to polishing (faceting) surface 110 (FIG. 1.). The leveling process takes place upon completion of the first facet polishing. Once oriented in such a way axis 160 always returns to its spatial orientation upon completion of the next facet polishing, may indicate to the operator the end of the facet polishing process. Since the length of insert 130 substantially exceeds the thickness t of front part 108 it makes assembly of 142, of pedestal 140 and dop holder 144 that lean on both ends of insert 130 sufficiently rigid. Due to the rigidity of assembly 142 axis 160 maintains its spatial orientation in course of diamond polishing with respect to tang body 102. The axial movement of axis 160 is restricted by the tension applied by spring 158 to machined end-faces 136 and 156 and pin 164 restricts rotational movement of pedestal 140 with respect to dop holder 144. O-rings 168 and 170 prevent occasional free rotation of assembly 142 and accordingly of pedestal 140 relatively to elongated tang body 102. The extended length of insert 130 and associated with it assembly 142 provides a more stable support for axis 160 and effectively reduces or eliminates any axis 160 wondering.

Level 124 provides visual feedback or control of the spatial position of axis 160 in the course of the leveling process. Level 124 may be positioned on surface 174 of pedestal 140. Level 124 has guiding means implemented as a circular depression coupled with guiding means (protrusion) 146 of pedestal 140. Level 124 may have guiding means implemented as a protrusion if the pedestal guiding means are implemented as a recess. Guiding means 146 serve as an axis and level 124 may be rotated on them 360 degrees or at least 90 degrees. For control of the leveling accuracy of tang 100 and rigidly associated with it axis 160 level 124 as shown in FIGS. 3A and 3B, is oriented sequentially along two mutually orthogonal axes such as X-axis and Y-axis or vise versa. When oriented along X-axis level 124 indicates pitch 118 and when oriented along Y-axis level 124 indicates roll 120 of tang 100. In order to increase the measurement accuracy, level 124 readings are taken in two positions. The first position reading is taken when level 124 is oriented along X or Y axis, where for the second position reading pedestal 140 is rotated 180 degrees. Upon completion of the tang leveling level 124 may be removed from pedestal 140, dop 128 is released and rotated on a predefined angle and the next diamond 122 facet polishing process may begin. The leveling process may be simplified by the use of a round or bubble level, although the accuracy of the commercially available levels is not sufficient for this purpose. Due to the rigidity of assembly of pedestal 140 and dop holder 144 axis 160 returns at the end of facet polishing to its orthogonal position to the polishing disk surface 110 making all of the facet angles equal.

The permanence in the position of axis 160 is achieved by the rigidity of assembly 142 and length of insert 130. The extended length of insert 130 is required since almost all tangs have even thickness of elongated body 102 including front 108 end. This thickness does not provide a sufficiently rigid support. As such, the method disclosed may be implemented on any existing tang. In another embodiment shown in FIG. 4, tang 190 has an elongated body 192 having front end 198 and rear end 194. Front end 198 is substantially thicker than the rest of body 192 and it has a machined surface 200. This thickness is comparable with the length of insert 130 and is selected such as to provide the rigidity required to prevent axis 160 wondering.

The disclosed method of polishing diamonds 122 is characterized in that diamonds 122 to be polished are held by a tang 100 having a rigid axis 160 leveled once to be orthogonal to polishing surface 110. Axis 160 returns to its leveled spatial orientation at the completion of each facet polishing process. Axis 160 maintains its spatial orientation with respect to the body 102 of tang 100 in the course of diamond polishing and when diamond 122 position is switched (rotated) between the facets to be polished.

The method of polishing gemstones and in particular diamonds disclosed leads to better quality of the polished diamonds and ensures higher yield of the polishing process.

A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other embodiments are within the scope of the following claims. 

1. A tang (100) for polishing diamonds, said tang comprising: a) an elongated body (102) having a rear part (104) and a front part (108), characterized in that a rigid insert (130) having a length exceeding the thickness of the front part (108), is inserted in the front part (108); b) an assembly (142) of a pedestal (140) and dop holder (144) that mechanically interfaces with the insert (130), and; c) wherein the assembly defines an axis (160) having a fixed spatial position with respect to said elongated body (102).
 2. The tang (100) of claim 1, wherein in use the tang (100) is leveled such that the axis (160) is placed in a position orthogonal to polishing surface (110) and the axis (160) returns to the orthogonal to polishing surface (110) position at the end of each facet polishing process.
 3. The tang (100) of claim 1, wherein the insert (130) has both of it, end surfaces (136 and 138) machined.
 4. The tang (100) of claim 1, wherein said dop holder (144) has a section (152) with a machined surface (156) leaning on the machined end face (136) of the insert (130), the section (152) is having an external diameter larger than the outer diameter of the insert (130).
 5. The tang (100) of claim 1, wherein the pedestal (140) has guiding means (146) serving as an axis for level (124) rotation and two O-rings (168 and 170) that prevent occasional rotation of the pedestal (140) in the insert (130).
 6. The tang (100) of claim 1, wherein and a spring (158) and a screw (154) tension the assembly (142) of pedestal (140) with dop holder (144).
 7. The tang (100) of claim 1, wherein the dop holder (144) has a section coupled with the pedestal (140) tubular stem (148) along a common axis (160).
 8. The tang (100) of claim 1, wherein for control of said tang (100) leveling a linear level (124) is removably mounted on the pedestal (140).
 9. The tang (100) of claims 1 and 8, wherein the level (124) rotates on said pedestal (140) at least 90 degrees.
 10. A method of polishing diamonds, comprising: a) providing a tang (100) of claim 1, a diamond (122) to be polished and a polishing surface (110), the method characterized in that it further comprises: b) adjusting the diamond (122) polishing angle, polishing a facet of said diamond and leveling the tang (100) such that axis (160) becomes orthogonal to polishing disk surface (110); c) releasing and rotating the dop (128) on a predefined angle to polish at least one additional facet of the diamond (122), and wherein the axis (160) returns the original orthogonal position to the polishing disk surface (110) upon completion of diamond (122) facet polishing.
 11. The method according to claim 10, wherein the leveling of the tang (100) in two mutually orthogonal axes is performed with the help of level (124).
 12. The method according to claim 10 and 11, wherein for reading the level (124) indications the level (124) is placed on the pedestal (140) and the pedestal (140) is rotated 180 degrees.
 13. The method according to claim 10, wherein the release and rotation of the dop (128) do not change the spatial position of the axis (160).
 14. A method for polishing diamonds, characterized in that diamonds (122) to be polished are held by a tang (100) having a predefined axis (160) orthogonal to polishing surface (110), the axis (160) returning to its original spatial orientation with respect to the polishing surface (110) at the end of each facet of the diamond (122) polishing.
 15. A device (100) for polishing diamonds, characterized in that it has a predefined axis (160) orthogonal to a polishing surface (110) and the axis (160) returns to its original spatial orientation at the end of each facet of the diamond (122) polishing. 